Moreover, by (REF ) and Lemma REF , the maximum transmit constraint of the ground source is given by [1]}
\(\mathbb {E}\left[|\mathbf {\mathrm {x}}|^2\right]=\mathrm {tr}\left(G_{\mathrm {s}} \mathbf {\mathrm {PV^{\mathrm {H}}V}}\right)=G_{\mathrm {s}}\sum _{m\in \mathbb {M}} P_m\le P_{\mathrm {max}},\) 
